1. Field of the Invention
This invention relates generally to the field of gauge and tank sampler devices and, specifically, to a dip stick for measuring the amount of liquid in a deep container such as an underground petroleum storage tank.
2. Description of the Prior Art
A variety of liquid level indicators are known in the prior art. One of the simplest is the dip-stick, which is an elongate member typically formed from wood or metal which can be inserted into an underground tank and then withdrawn, the liquid level in the tank being determined by observing the height to which the liquid has wetted the dip-stick. The wetted height on the stick is compared with a suitable calibration. The calibration could be, for instance, in the form of an external chart or in the form of graduations imprinted on the dip-stick itself.
Although the traditional dip-stick is a simple and economical means of estimating liquid levels, it suffers from several disadvantages. Although it is capable of measuring the level of liquid in the tank, it ordinarily cannot distinguish between one liquid and another (for example water and gasoline). It gives no indication of the character of the liquid, such as whether the liquid is clean or dirty.
Another disadvantage of the simple dip-stick is the lack of precision in the level reading which is obtained. Conventional dip-sticks generally rely upon the surface attraction between the material of the stick and the liquid to provide an observable, wetted surface level indication on the face of the stick. In order to provide a more precise reading, the stick may be powdered in an attempt to better delineate the liquid level. However, wave action in the tank or capillary action of the liquid contacting the powder can cause inaccuracies in the reading.
Accordingly, the present invention has as its object to provide a simple and convenient way to more accurately measure the liquid level of liquid in a container, such as an underground liquid storage tank.
Another object of the invention is to provide a device and method for measuring liquid level in an underground liquid storage tank which does not rely upon the low surface attraction between the exterior of the stick and the liquid in the tank.
Another object of the invention is to provide a level indicating device which also allows sampling of the liquid in the tank to provide an indication of the character of the liquid and which is capable of distinguishing between one liquid and another.